Mats Nordlund wrote: > Hi, > > I have just succeded in setting up RTAI 3.4+RTNet 0.96 using 2.6.17. I had > to replace RTAI3.4's whole /addons/rtdm in order to avoid the "nanosecs > problem" (see > http://www.mail-archive.com/rtnet-users%40lists.sourceforge.net/msg01441.html). > > I replaced all files with the contents of magma's /addons/rtdm. This made > the compilation to work. > > However, now I think that something related to the "time_stamp function" > may > have been corrupted. > > Capturing packets using Wireshark (former Ethereal) on rteth0 works fine > after "rtnet capture" is started. However, when I examine the capture file, > I can see that several packets that have the exact same time stamp (the > intermediate time is therefore zero).
Likely, those packets were received by the same IRQ event. The typical
RTnet driver looks like this:
irq_handler()
{
timestamp = read_timestamp();
...
while ((packet = incoming_packet())) {
packet.timestamp = timestamp;
enqueue_received_packet(packet);
}
...
}
If you think this is not the case here, post your trace (or relevant
fragments).
> Also, I only get microsecond
> resolution in the capture file (the last digits corresponding to nanosecs
> are all zeros).
That's due to the fact that Linux "only" handles timestamps via struct
timeval, i.e. with microsecond resolution. But that's ok as the error of
your timestamp is in microsecond range anyway, even on unloaded passive
sniffers.
>
> One additional thing is that I am running with the experimental drivers for
> the 3Com NICs (3c59x). Maybe this is the root cause for the time stamp
> problem?
That driver can cause long delays on certain error conditions (which are
not fully analysed, thus the warning), but it should work otherwise.
Jan
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